1. Field of the Invention
The present invention relates to an electronic watch that performs two-way data communication with an external device.
2. Background of the Invention
As multi-function watches have progressed in recent years, there have appeared many systems in which an IC within a watch has a variety of data. For example, there is the case in a watch having a sensor, in which setting data is provided for the purpose of adjusting the sensor sensitivity and offset at the time of manufacture, and the case in which, when a watch is actually used, various measurement data obtained by sensor operation are stored within the watch beforehand, measurement data being displayed in response to the needs of the user.
Even in a watch without such added functions as sensing, frequency adjustment of the internal reference signal source of the watch is almost always required when the watch is completed.
In a watch having a system in which setting data when frequency adjustment is done is held in a memory inside an IC, frequency adjustment is performed either in the condition of a circuit board onto which are mounted an IC and a quartz crystal, or as a movement, in which case data is often set into the IC by using a writing system that is electrically connected to the circuit board.
In order to achieve a more accurate frequency adjustment, a problem arises with the above-noted method.
Specifically, in the case in which a circuit board or movement is built into a watch case, the oscillation frequency of the reference signal source can shift because of floating capacitance and the like, and the stress applied to the quartz crystal upon mounting into the case can also cause a change in the frequency.
In the above-noted cases, the ideal approach is to adjust the frequency after mounting the movement into the watch case and completely closing the rear cover.
However, the provision of an electrical contact after mounting the movement into the case sacrifices watertight integrity, reduces noise immunity, and presents various restrictions on design.
Therefore, in order to perform writing of frequency adjustment data into the IC after mounting into the case, it becomes necessary to perform contactless transfer of data to an IC on the circuit board.
In a watch that includes a sensor, even in the case in which measurement data is to be transferred to an internal device, this is usually performed using a system with connection contacts, although this is accompanied by a variety of adverse effects, as noted above.
With respect to these problems, a method disclosed in WO 94/16366 is one in which the motor coil of an analog watch is used to perform data transfer electromagnetically between the watch and an external device, data transfer being performed in accordance with a timing signal from the watch, so that data transfer from outside the watch is possible without disturbance to the drive of the watch hands.
It is possible using the method of the past to input data and the like to a watch from outside the watch without at all affecting the normal drive of the watch hands.
However, in the case in which data is input to a watch from outside during the interval between step movement of the watch hands by applying a magnetic field, if an excessively strong magnetic field is applied, not only is the hand drive greatly affected, but also there are cases in which the externally applied magnetic field can even cause the hand drive motor to rotate.
In the case in which the watch circuitry in an analog watch is configured with high sensitivity so as to enable reception of external data and the like even in a weak external magnetic field, it can be envisioned that external magnetic noise can cause faulty operation in the watch when it is in normal use.
Accordingly, an object of the present invention is to alleviate the above-noted problems in the prior art by providing a system which performs reliable transmission of the required data, for example, from a prescribed data transmission unit to an electronic watch, and which completely eliminates the influence on the basic functioning of the electronic watch.
In order to achieve the above-noted object, the present invention has the following basic technical constitution.
Specifically, the present invention is a data transmitting/receiving system in an electronic watch which is configured by an electric watch and a data transmitting unit, separate from the watch, which generates a data signal, a coil within the electronic watch being used by a data receiving means of the electronic watch to receive a data signal from the data transmitting means, the above-noted electronic watch having a timing signal generation means, which generates a timing signal, and the above-noted data transmitting means having a timing signal receiving means, which receives a timing signal which is output from the above-noted timing signal generation means, the data transmitting unit transmitting a data signal to the electronic watch in synchronization with the received timing signal, and the data receiving means in the electronic watch receiving the data which is sent from the data transmitting unit only with a timing at a time when the data is sent from the data transmitting unit.
A more specific configuration of a data transmitting/receiving system of an electronic watch according to the present invention is a data transmitting/receiving system in an electronic watch which is formed, for example, by a data transmitting unit, which generates a data signal, and a data receiving means which receives the data signal from the data transmitting unit, using a coil of a motor used to drive the hands of an analog watch, the electronic watch having a timing signal generation means, which generates a timing signal, the data transmitting unit being provided with a timing signal receiving means, which receives the timing signal output from the above-noted motor coil, the data transmitting unit transmitting the data signal in synchronization with the receiving of the timing signal, and the data receiving means performing receiving of data only at the time of transmission of data from the data transmitting unit.